Method for measuring and reporting co-oximeter quality control results

Abstract

The present invention comprises methods of determining the performance of an absorbance spectrometer, and, in particular, of CO-oximeters. The methods comprise measuring the absorbance spectrum of a quality control sample and comparing it to a standard spectrum of that quality control. Instrumental error will be the primary factor contributing to the observed difference. The present method also provides techniques for converting the instrumental error manifested in the difference between the measured and standard quality control spectra into blood concentration values comparable to that of real blood. Analysis of test samples on a spectrophotometer; and calibration of the spectrophotometer is also provided.

I claim: 
     
       1. A method of determining the quality of performance of an absorbance spectrometer, the method comprising: a. measuring the absorbance spectrum of a quality control sample;   b. fitting the measured sample spectrum with the standard spectrum of the quality control sample to obtain a best fit spectrum and an apparent concentration of the quality control sample; and   c. evaluating the quality of the fit.   
     
     
       2. The method, according to claim 1, wherein the quality of the fit is evaluated by calculating the difference between the best fit spectrum and the measured spectrum to yield an error spectrum. 
     
     
       3. The method, according to claim 1, wherein the quality of the fit is evaluated by determining the deviation of the apparent concentration of the quality control sample, c app , from a standard concentration of the quality control sample, c std . 
     
     
       4. The method, according to claim 2, wherein a least squares analysis is used to fit the standard spectrum to the measured spectrum. 
     
     
       5. The method, according to claim 3, wherein a least squares analysis is used to fit the standard spectrum to the measured spectrum. 
     
     
       6. The method, according to claim 1, wherein the quality of the fit is evaluated by fitting one or more blood component spectra to an error spectrum to yield errors in concentration of blood components. 
     
     
       7. The method, according to claim 6, wherein a least squares analysis is used to fit the standard spectrum for the quality control sample to the measured spectrum and to fit the one or more blood component spectra to the error spectrum. 
     
     
       8. The method, according to claim 1, wherein the quality of the fit is evaluated by selecting a nominal total concentration of hemoglobin, multiplying the nominal total concentration of hemoglobin by the apparent quality control sample concentration to yield an apparent total hemoglobin concentration. 
     
     
       9. The method, according to claim 8, wherein a least squares analysis is used to fit the standard spectrum for the quality control sample to the measured spectrum. 
     
     
       10. The method, according to claim 6, wherein the quality of the fit is evaluated by selecting nominal values of concentrations of the blood components, adding the errors in concentrations of blood components to their respective nominal concentration values to yield apparent concentrations of the blood components, and evaluating the apparent concentrations of blood components. 
     
     
       11. The method, according to claim 10, wherein a least squares analysis to used to fit the standard spectrum for the quality control sample to the measured spectrum and to fit the one or more blood component spectra to the error spectrum. 
     
     
       12. The method, according to claim 10, wherein the quality of the fit is determined by selecting a nominal total concentration of hemoglobin, multiplying the nominal total concentration of hemoglobin by the apparent quality control sample concentration to yield an apparent total hemoglobin concentration, and dividing the nominal concentrations of hemoglobin components by the apparent total hemoglobin concentration to obtain fractional concentrations of hemoglobin components. 
     
     
       13. The method, according to claim 6, wherein the concentration of blood components are weighted to reflect anticipated instrument variations. 
     
     
       14. The method, according to claim 1, wherein said standard spectrum of the quality control sample has similar connotations of one or more absorbing components of the quality control sample. 
     
     
       15. The method, according to claim 1, further comprising the step of measuring the absorbance spectrum of a test sample. 
     
     
       16. A method of performing absorbance spectrophotometer analysis comprising: a. measuring the absorbance spectrum of a quality control product;   b. fitting the measured spectrum with a standard spectrum of a quality control product having the similar concentration of one or more absorbing components to obtain a best fit spectrum and an apparent concentration of the quality control product;   c. evaluating the quality of the fit; and   d. measuring the absorbance spectrum of a test sample.   
     
     
       17. A method for calibrating an absorbance spectrophotometer comprising: a. measuring the absorbance spectrum for a plurality of quality control samples, wherein said quality control samples correspond to a blood component spectra;   b. fitting the measured spectrum with a standard spectrum of a quality control product having the same concentration of absorbing components to obtain a best fit spectrum and an apparent concentration of the quality control samples;   c. evaluating the quality of the fit; and   d. adjusting the calibration of said spectrophotometer.